Cleft construction “designed” for focussing one XP of a clause is used in the sentence above to mark the whole clause as focussed. The effect is achieved by extracting the usual topic of a sentence – ...

THERE are times when we just feel that even the passive voice falls short of giving us the desired emphasis for what we want ...

Cleft sentences are used to help us focus on a particular part of the sentence and to emphasise what we want to say by introducing it or building up to it with a kind of relative clause.